Bidirectional counter



Oct. 20,

1953 B. MCMILLAN 4BIDIRECTIOML COUNTER Filed Oct. 28,v 1949 Patented Oct. 20, 1953 UNITED` f ,OFFIC n K BYIVDIRECTIONAL COUNTERy y ,BrockvvayyvMcMillam Summit,N.- J., assigner 'toY Bell Telephone Laboratories, Incorporated, New

lYork, N, Y., Va corporation,ofrNewI5 York Application October 28, 1949,'Serira'l No.124,195

15,'Claimsr .This 'invention relates -to countingv means' and moreparticularly to electronicxcounting circuits capable :of bidirectional oper-ation. v y

Anobject ofl thisinvention is -tofprovide'an electronic counting circuit operative'eitherto add orsubtract, i.e.,V either to count oruncountffl *Another-object. of this invention .is `to furnish anelectroniccounting circuit readily. modifiable to4 count on any selected base. i n 'A further object of this-invention is .'-to `provide a=bidirectional countingcircuit capable of countingV physical-phenomena `occurring fat highrates of speed without the necessity` of ydelay networks and :without requiring incoming pulses-toi perform interval switching. 'E VThes'eobjects have been .accomplished in `the preferred embodiment of the invention by prolviding a pluralityxof `sets of trigger, circuits-.or dip-flops each"comprisingA a fpairiof electron discharge devices. Each Cif` these-pairs .is initiallyA set in acertain state.fA^pulse`to be counted is amplified. iand appliedy so "as to reverse` `.the state ofuthe first*v trigger circuit.f This.-operationnotonly vregisters the, first count butvialso opens anelectronic'gate circuit .comprising elements of the then-conducting electron discharge device. The next pulse to be countedffis. then transmitted through this gate, amplified, and; applied to reverse the s'tateof the next succeeding trigger circuit. Means .areprovided operativein `response to a pulseY transmitted through the-gate of the last trigger circuit in anyone stage-to reset allip-fiops in that stage. =Thecircuits"are arranged tobe fully symmetrical-whereby they areiresponsive to pulsesto be subtractedorun'- counted in a manner similar 'but -eXactlyoppo'- site tothat in which they respond to additive pulses." The circuits ycomprise a repetition'of'fa few simple substructures fand -a vcounter lfor Aany suitablescale may readily be contrived by a;sel`ec;- tionof the properV number of'substages. z

r'The invention may be more fully-understood fronrthe following. detailed description of the invention, with reference` tothe accompanying drawing showinga preferred embodiment of the invention. T-he drawing discloses one'stage-.ofa Ycounterfor the-scale-'of three. As will benoted from the ensuing description,l 'the circuits 'may readily beV contracted or expanded tovcount on anydesire'd base. For example, the addition Iof seven rmoreV pairs of counting :tubes fand associated circuits Will-provide a system operativefto count ldecimally.:` t Wi1l1further Vbenoted that the circuit is perfectly symmetrical ask between additive and subtractive countsv Iny -fact,: the

diagramof glig. `v1- may be- `rotated .180 degrees Withoutichange;fa The basic fcircuitfutilizedin the presentzcounteris a modicationof-the Well-knowngEccles- Jordan triggencircuit as disclosed Ain British Patent-148,582,y accepted August 5, v1920, and; as shown in aevarietyof forms--in'fTheorycand Applicationsof Vacuum sTubes Yby Herbert J. Reich. Anelementary'form ofthat trigger circuit comprisesrtwo triodes 4inv whichthe controlvgrid of eachtubeisncoupled 'tok the anode of the other ktube through aparallel-connected resistance-.capacitance network..v VThe cathodes of theftubes are :normally `grounded,fvvhileVA suitable operating grid and anode .voltages are supplied through vre sisters individual, to those electrodes,y Iranegative `voltage be momentarily :applied to the grid ofthe firsttriodepthezanode current of vthat tube `Willibe reduced whereby the anode potential will 4stable in -this'condition until a negative pulse is appliedrto .the controlggridlof theconducting ytriodef or apositivepulse to the controlgridof kthe non-conducting'triode)\ which will initiate a-transfer-to ,the opposite stable state wherein .the'irst triode is rendered conductive and the secondtriode iscut off; g

. 'In each stage Aof-the electronic counter herein disc1osed,one lessr pairof trigger tubes is lemployed than theV counting base. `In the-depicted embodiment, an vexemplarycale Vof three has been used' with A,two trigger circuitsbeing provided. `For a purpose hereinafter to-bef'fdiscussed,I pentodes -Plj yand P2 are employed as the tube `elements of one substage and pentodes P3 Aand P41 are employedas the ltube elements of thev next succeeding substage. -Thesefpentodes should be -ofa type, such astneASGyin which alligridsi are vavailablesfor use; vThreeY elements of eacha'tube are'employedA as a triode section, and circuitry is associated Y with these electrodes of each pentode pair Ato provide at trigger. circuit. In the pentodes PI and P2, the cathodes are grounded, the rst grids: lolvand :I02farefemployed as the control grids of the tride sections, and the second grids ID3 and IM, normally employed as screen grids, are utilized as the anodes of the triode sections. The triode-section plate 103 of pentode Pl is connected to a positive G-volt supply voltage through load resistor Rl and is coupled to the control grid of the triode section of pentode P2 through the network comprising resistor R2 and capacitor CI, in parallel, and via conductor H15. Similarly, and symmetrically, the triode-section plate |04 of pentode P2 is connected to a positive 15G-volt supply voltage through load resistor R3 and is coupled to the control grid of the triode section of pentode PI through the network comprising resistor R4 and capacitor C2 and via conductor IEB. Since, as Will be seen hereinafter, the-,circuits are preferably triggered by pulses of short duration, capacitors Cl and C2 are provided to obviate the difliculties arising from interelectrode capacitance. To provide the necessary operating grid voltages, control grid il of pentode Pi is connected to a negative 15G-volt supply voltage through resistor R5, and the control grid 102 of pentode P2 is connected to this same source through resistor Rt. This circuit is a conventional iorm of Eccles-Jordan trigger circuit as above described and, with proper parameters, will be operative to render the triode sections of pentodes Pi and P2 alternately conductive either upon the alternating application of potentials of opposite polarity to the control grid of one of the tubes or upon the alternate application of pulses of a single polarity to the control grids of the two triode" sections.

Indicators may be provided to show in which of the stable states the trigger circuit is at any given time. These may be neon lights shunting the plate load resistors Vof the triode sections of one of the pentodes in each substage. Thus, neon light Nl is placed in shunt of resistor Rl and will glow only when the triode section of pentode Pl is conducting.

' Itv may be noted at this time that the substage comprising pentodes P3 and P4 is interconnected identically with that above-described to provide a trigger circuit in that substage, and the same applies in each other substage which may be provided.

The remaining elements of each pentode, i. e., the third (suppressor) grid and the anode, in cooperation with the other elements which act conjointly as a cathode, form a gate circuit. Negative voltage is normally applied to the third grid of each of the pentodes to prevent plate current from flowing in the pentode regardless of the state of the triode section of that pentode, i. e., regardless of whether there is or is not a suitable potential on the first or control grid to cause current to flow between the second (screen) grid and cathode of that tube. If, while the triode section of any of the pentodes is conducting, a positive pulse be applied to the third grid of that pentode, plate current will momentarily now. If, however, the positive pulse is applied to the third grid While the triode section of that pentode is not conducting, conduction through the tube is prevented and plate current will not flow. Therefore, these elements of `each pentode act as a gate continuously operative to prevent plate-current ovv, but operative to cause the plate current to flow only when the triode section or trigger section of that tube is conducting.

The input pulses controlling the above-described operation of the pentode may be applied through a triode serving as a buier amplifier and phase inverter. Considering the substage comprising pentodes Pl and P2, additive pulses, i. e., pulses which add to the pulses already registered in the counter, are received at the count terminal lill and are 'applied through capacitor C3 to the grid of triode BI. In the preferred embodiment, with the tube types herein employed and with the representative circuit parameters hereinafter disclosed, these pulses may be of negative 50-volt amplitude and of about 2 microseconds duration.

The anode of triode Bi is grounded through resistor R1, the cathode is connected to negative 15G-volt supply through resistors R8 and R9, and the control grid is connected through resistor Ri to Ya point in the cathode circuit intermediate resistors RB and R9. It may be noted that the value of resistor R8 is determined by the operating characteristics of tube Bl, and may be omitted in some cases. The parameters of the circuitare so adjusted that in the normal or quiescent condition of triode BI, the plate potential, controlled by the potential drop across resistor Rl, is such that the third (suppressor) grid of pentode PI is held sufficiently negative relative to ground that no plate current Will flow in that pentode, Whatever the state of the triode section thereof, as above mentioned. For pentodes of the type 6AS6, a potential of about negative l5 volts will suice. The cathode of triode Bi is coupled to the rst grid (the control grid of the triode section) of pentode P2 through capacitor C4 and conductor |85.

Let it now be assumed that the triode sections o pentodes P2 and P4 are conducting and that the triode sections of pentodes Pl and P3 are not conducting. The condition of any ipnop or trigger circuit in which the lower tube (P2, PA, etc.) is conducting and in which the upper tube (PI, P3, etc.) is not conducting, may hereinafter be referred to asV the zero state of the flip-flop or trigger circuit, While the opposite condition may be called the one state. When a negative counting pulse is applied to the grid of tube BI through capacitor C3, current iiow through that tube will be reduced with a consequent momentary rise in anode potential and momentary reduction of cathode potential thereof. With the trigger circuit in the substage comprising pentodes Pi and P2 in the zero state, the momentary rise in anode potential of tube Bl, as applied to the third grid of pentode Pl, is ineiective to cause plate current to iiow in tube Pi since the triode section of that tube is not conducting. The momentary reduction of cathode potential of tube BI is applied as a negative pulse through capacitor C4, conductor |05, and to the control grid of the triode -section of tube P2. This pulse is sufficient to cut ofi` the triode section of tube P2 and to render the triode section of tube PI conductive in the manner hereinbefore described. By this action, the substage comprising tubes PI and P2 is triggered to the one state.

It may be collaterally remarked at this time that the pulse duration must be short enough so that the third (suppressor) grid of tube Pi will have reverted to its normal negative potential by the time the triode section of that tube has been rendered conductive, i. e., the pulse duration should be shorter than the transfer time of the flip-flop.

The next negative pulse received at the count" Y across resistor RI I, a negative pulse' will be'transmitted through capacitor"65` to thei'grid voftri- It may be seen at this'timel that, assumin'g'the trigger circuit to be in the A`zerestatefthe'iirst incoming pulse to be counted will serve totrigger the circuits of the first substage tothe one state,and the second incomingpulse/will then be lga'tedthrough to the next substage. Thefcirlcuits vof each subestage are identical* Infthe second depicted substag'efpentodes P3 and `P4 are the correlatives'of pentodes PI'and P2',"and

triode'B2 is thecorrelativeof triodefBI `As'will f be seen'hereinafter, 'triodefBlIrin thesecond substage is thej correlativa of Vtriode B5 the rs't shown vsubstageftriode lB3^in the next succeeding "substage 'or stage is the 'correlative" of triodes` `B I and B2., and triode B6` in the nextprecedingsublf stage or stage is' the correlative loftriodesfB Thefreceipt'of-the second pulse to be' counted affects the second substage in thesamemanner lthatthe firstfpulse'affected the 'first f substage fas-fabove'described; i; `e: it triggers"'the"s'econd substage to its 1one-state whereinthe triode section of pentode P3l is rendered conducting'. The vthird pulse to bebounted is gated' through pentode PI of the rst substagejandis amplified an'd inverted by-tube -B2-and applied t'o'the third (suppressor) grid of pentodeA IP3 lto open Athe additiVe-gate of the second ALs'ubstage.4 `A-"negative pulsefwill'thereby be `applied through capacitor C6` to the grid of triode B3 in the next substage.

The arrows `at the anode and cathode kof tUbeB3 indicate connections'to pentdes in the next `substagev orstage correlativeto pentodes PI and'PZ Therefore',Y with -lth'e' depicted circuits being taken to represent one stage of a counter for-I-th'e scale off three-the count in the stage is registered Iinl accordance withfthe following' table in `which On orrOf indicates whether `thewttriode 'section ofthe pentode-isconducting orno'n-"con- .'Illfie'nlegative pulseat `the vgrid oftube B3,- fre sulting from the receiptof thevthird add pulse,

is also applied, viathat gridand through capaeie. torCl, tothe control grid ofrtriode TI. Triode y' I'I anditscorrelative triode T2., eaehin cathode follower connectionare used. to provide reset signals upon completion of the countin the stage.

Theanode oftube .TIKis connected 4to positive; 'I5-,volt battery, and the cathode is connectedto negative 15G-volt battery throughvresistor RI 2. TheV control gridfis,` connected to positivel'fvolt battery through resistor RI 3 and to negative 150- .volt battery through'resistor RIA. y.The value "of resistors RI3 and RM is so adjustedv thatf'due'to .6 the --voltage drop across resistor l1R. I 2`,":the-cathode of triode TI will normally be a` few volts--suchas 10`positive relative to ground. Thusfal" positive" rpotential `will be 'appliedg via-l conductor y I D8, to Y' the high impedance side *of rectifiers fDI and D3. l These `elements may be dryl -rectiers;`crys2 taldiodes,gaseous'fdiodes,` etc.; and are connected lso V"that they i present a low-impedance to con- -ventienal"currenty flow-througlr then and A'toward the'cathodeo'f tube TI The low-impedance'side of'rectier DI `-isconnectedf t'othe lfirst "(control) grid IUI of pentode PI, and theflow impedance side fof rectifle'r D3 is' 'connected tothe:first` (controlVgridl of pe`ntodeP3.'` 'These controlgriiis operate betweenv ground potential .and some point considerably below vgroundl'potential; Therefore', the rectiersflD I f and yD3- are always." biasedf at leastY ten .voltsl in the reverse direction. With thisreverse' potential, rectier's'D'I and D3 'reprel sent V"relatively high resistances Which'join'at the cathode' of tube TI. Since tube TI is'a cathede follower, the veffective impedance at its cathode `is low. There is, therefore, normally little chance offceuplngb'etween the first and second'trig'ger eircuit's or f1ip'fiop's through 'these biased'recti- .er paths. el.; When a negative pulse appearson the control gridlof 'tube Tl,"however', }the"`eathode 'of that tuberepeats the negatvepulse dueto the momentary reducedpotentialdro'p through resistonRIZv. Since both pentodes PIV and "P3 are on at this time of thecycle; thefirst (controligrids therefof are at'a potential" near ground.' The pulse imm the .Cathqde oii-'ubef'll ,can thencpull .the rectifiersfDl .and Dfnegeve andfwll .belen Athe peint :where .therbecome 19W impedenefpethS to.; the .,rst @Qntrel) grdyofentdes, PI .and P3. Thesglst lende will. ihenbe driven' lto .a negative.A potential bythe W. impedance` genera-- -tor represented 'Y by i the cathode output of tube Pl despite any. eioiflQi {th-higher,inibedeffe generator, -.vrg apresentedfl by' 1the second; grids (,fanodesfgk offohe tringle,y sections); ,of tubes-= B2 andfPfl `G0 hold them positive; i-Therefoehis third negative-pulse -Wll CauSe.- erstngx-'GO occunby hatienne` the, cutting Vofllof,tilbes.' and P3 to restore thefvstage t0 vtheassumed initial condition in which pentodesPZ and Piweresconducting.--;- I e As rhereinbefore Inentioned,

Pulses -1 appearing` .at the Y funcount` terminal:v I 09 'are eff ective 1in a; manner; identical with4 that; de'- scribed regard to :additive pulses, -bll produce .-a. result exactly .opposite` Thus, assumeagain `that thecircuit isf initiallypinmthe condition 0...as

shown in` the r'st. line: y.offthe .abov'eptablefiI A negative" pulse ioni .uncoun A'termina-l l1109 zWill 'pass through `the fopen gate i of*v tubes .P45 and .1?2,

and be applied through` triode :B6 as Ptaffcarry tothe nextI preceding substaug'elorstage. fi-This vpulse lwill also be:l appliedftdthe l-gridoff-tri'o'dew'l? to "cut off pentodesv P2" and? P4 infaI manner similar to that rabove described for'the additivepul'se 'resetting operation. he'f depicted stage Jis then in the'cohdinn; 2f ascendingV to' `theL aboveftable, e.'v,-"in the `cyclic arithrnetic ofv'a -singlestage Aone less `than Zero;- The neiit negative :lpls'e 'at completely symmetrical to the `forward counting -cycle. v p

It may be noted that to draw the. diagram of one stage of a counter for any base B, one simply continues the chain of pentode flip-flops and vtriode buier amplifiers to include B-l flip-flops, and then drives the reset tubes Tl and T2 from the plates of the right-hand upper pentode and the left-hand lower pentode. The inner grids of all upperpentodes are connected through rectiers to the cathode of reset tube Tl, and symmetrically below.

The `B-series and T-series triodes could all conveniently be half-sections each of double triodessuch as type 2G51. The following are exemplary circuit values for 2G51 double tricdes, 6AS6 pentodes, and the supply voltages shown:

'Rl ohms 20,000 R2 do 40,000 R d0 75,000 Rl do 4,000 R8' do 0 R9 do 12,000 RIU do 200,000 RII do 20,000 R12 do 15,000 R13 do 200,000 RM do 500,000 CI micromicrofarads 50 C3 d0 250 C4 do 10 C6 do 250 The rectiers may be crystal diodes of Western Electric type 400A or Sylvania type m39. The

circuit elements not mentioned in the above list appear in positions similar or symmetrical to the position of some element above listed.

It is to be understood that the suggested circuit parameters, tube types, and polarities of signal voltages, are purely exemplary. It is further to be understood that the above-described arrangements are illustrative of the application Voi.' the principles of the invention. Numerous 'other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. A bidirectional pulse-counting circuit comprising a plurality of trigger circuits each having two stable states, an additive impulse input connected solely to the first of said trigger circuits, a subtractive impulse input connected solely to the last of said trigger circuits, the rst of said trigger circuits when in one of said stable states being operative in response to a pulse on said additive impulse input to transfer to the .other stable state, means individual to each of said trigger circuits when the state of the associated trigger circuit has been transferred for transmitting a pulse from said additive impulse input through all the preceding trigger circuits the state of which has been transferred to the next succeeding trigger circuit, the last of said trigger circuits when in one of said stable states ,being operative in response to a pulse on said subtractive impulse input to transfer to the other stable state, and means individual to each of saidtrigger circuits when the state of the asscciated trigger circuit has been transferred for transmitting a pulse from said subtractive impulse input through all the succeeding trigger circuits the state of which has been transferred to the next preceding trigger circuit.

- 2'. A pulse-counting circuit comprising a plurality of trigger circuits each having a rst and a second stable state, pulse transmitting means individual to each of said trigger circuits, each of said trigger circuits when in said rst stable state being operative in response to a pulse from its associated transmitting means to transfer to said second stable state, and a gate circuit individual to and integral with each of said trigger circuits operative when the associated trigger circuit is in said second stable state and in response to a pulse from said transmitting means for transmitting a pulse to the next adjacent trigger circuit. s f

3. A pulse-counting circuit comprising a plurality of trigger circuits each having a first and a second stable state, pulse transmitting. means individual to each of said trigger circuits, each of said trigger circuits when in said rststable state being operative in response to a pulse from its associated transmitting means to transferto said second stable state but when in said second stable state being inoperative in response to la pulse from its associated transmitting means to transfer to said first stable state, and a gate cir cuit individual to and integral with each ofsaid trigger circuits operative when the associated trigger circuit is in said second stable state and in response to a pulse from said transmitting means for transmitting a pulse to the next adjacent trigger circuit. v Y

4. In a pulse-counting circuit, a pair of multielectrode electron discharge devices, means-interconnecting three of said electrodes of eachof said devices to form a trigger circuit, pulse input means, pulse transmitting means comprising an electron discharge device individual to said pair of devices and controlled by said pulse input means for applying a pulse to said interconnecting means to transfer conduction from one of said devices to the other of said devices, and means including said pulse transmitting means for normally applying a potential to a fourth one of said electrodes in at least one of said devices for preventing conduction through a fifth one of said electrodes in said at least one of said devices.

5. In a pulse-counting circuit, a pair of multielectrode electron discharge devices, means interconnecting three electrodes ofl each of said devices to form a trigger circuit, pulse input means, pulse transmitting means comprising an electron discharge device individual to said pair of devices and controlled by said pulse input means for applying a pulse to said interconnecting means to transfer conduction from one of said devices to the other of said devices, and means including said pulse transmitting means for normally applying a potential to a fourth one of said electrodes in each of said devices preventing conduction through a fifth one of said electrodes in each of said devices.

6. In a pulse-counting circuit, pulse input means, pulse transmitting means comprising an electron discharge device controlled by said pulse input means, a pair of electron discharge devices each having an anode, a cathode and three grids, and a pair of impedance branches interconnecting the second one of said grids of each of said devices to the Iirst one of said grids of the other of said devices to sustain the circuit in either of two alternative states and selectively condition,- able for reversal from either state to the other vin response to a pulse from said pulse transmitting means, and means including said pulse transmitting means for normally applying a potential to the third one of said grids in at least means including said pulse transmitting means fornormally applyingfa potentialto ,afourth one of said electrodes .in at leastonefof said devices preventing conduction 'through'a fifth one l of said electrodes in said one of saidldevices andY operative under the control of said pulse input means to apply a-potentialto said` fourth one of said electrodes permitting conduction through saidfthone of said electrodes@V l 8; Yapulse-counting circuit, pulse .'input means, 'pulse transmitting means ncomprising an electron discharge device controlled by said pulse input means, a pair of-electron dischargedevices each having an`-anode,a cathodeand three grids, and a pair of impedance branches interconnecting the second one` ofjsaid gridsof eachoffs'aid devices to the first onelof said gridsof the other of said devices tosustain the circuit `ineitherof two alternative states and selectively conditionable for reversal from either state to the other in response to a pulse from said pulse transmitting means, and means including said pulse transmitting means for normally applying a potential to the third one of said grids in at least one of said devices preventing anode current from owing in said at least one of said devices and operative under the control of said pulse input means to apply a potential to vsaid third one of said grids permitting anode current to flow.

9. In a pulse-counting circuit, pulse input means, pulse transmitting means comprising an electron discharge device controlled by said pulse input means, a pair of multielectrode electron discharge devices, and means interconnecting three of the electrodes of each of said devices to form a trigger circuit responsive to a pulse from said pulse transmitting means to transfer the conduction from between two of said three electrodes in one of said devices to two of said three electrodes in the other of said devices, and means including said pulse transmitting means for normally applying a potential to a fourth one of the electrodes of at least one of said devices for preventing current flow through a fifth one of the electrodes of said device and operative when conduction exists between said two of the electrodes in said at least one of said devices and under the control of said pulse input means to cause current to flow through said fifth electrode of said at least one of said devices.

10. In a pulse-counting circuit, a plurality of trigger circuits having a first and a second stable state, each of said trigger circuits being responsive to a first received pulse to transfer from said rst stable state to said second stable state, means individual to each of said trigger circuits operative when the associated trigger circuit is in said second stable state and in response to a received pulse for transmitting a pulse to the next adjacent trigger circuit, and means operative in response to the first pulse frallsmtd. by the 91.19 0f said, meansindividual .tothe last of said'trigger circuits totransferall .of-,said trisssrsirguitsgfg said iirst stable-state, the: .lest-mentioned; .means smsfisins Circuit including@ .rectifier findividus1ft0-ea0h :0f seid ,triggerA r'JIcilit-S.,l i

nime Circuit. srlurelitvfof irieesrsircliits Lses11 f1.1ari1s s Vrst and a secsnd ,stbilelstategeagh- .0f said trieeeruirssits being .responsive Y i0. 1 `s z-f11rsrsssivsd---pulse t0 transfer romssid first stable steigt@ said secondA stable ,stateifirst meses. .individual is, sash 0f ssidtrisf ser ,Qirsiliis YOperative when the' associated. iria serissuitis `is. seid; second, stable state. andi@ response., to s received pulse fer transmitting .a pulsevto the next adjacenttrigger circuit, anrecti- .ervndir iusl.is and, connected to sash. ,of said trigger-circuits, and means operative in response tothe `iirstpills@1frs11-s1ntts iby the 011s. 0i said first means individual to: a vcertain one, of `said triggerl :circuits .toapply apulse through said rectifiers to transfer eachof said trigger, circuits to :saidfirst stable state.`

,y 12,1111 ajpulse-counting circuit, 'of

trigger srsuitsseshihsvie s rst and, s s670011@ Stbl :Sti :each Ofi Saidtrggr rusbeing responsive to a rst received pulse `to transfer from-said rst stable state to said second stable state, irst vmeansinoflividual to each of fsavid hisserCir@HirsiOperative` .when the s'ssistsd trigger circuit is in'said second stable state'and in response to a received pulse for transmitting a pulse to the next adjacent trigger circuit, a rectifier individual to and connected to each of said trigger circuits, and means normally biasing said rectiiiers reversely and operative in response to the first pulse transmitted by the one of said rst means individual to a certain one of said trigger circuits to apply a pulse through said rectiers totransfer each of said trigger circuits to said first stable state.

13. A pulse-counting circuit comprising a plurality of trigger circuits each having a first and a second stable state, each of said trigger circuits when in said first stable state being operative in response to a pulse to transfer to said second stable state, a gate circuit individual to each of said trigger circuits and controlled by the state of the trigger circuit to which it is individual, an electron discharge device individual to each of said trigger circuits and operative in response to each pulse applied thereto to apply a pulse to both the trigger circuit and the gate circuit to which said device is individual, each of said gate circuits being operative when the trigger circuit to which said gate circuit is individual is in said second stable state and in response to the pulse applied thereto by the one of said electron discharge devices individual thereto for applying a pulse to the electron discharge device individual to the next adjacent one of said trigger circuits.

14. A pulse-counting circuit comprising a plurality of trigger circuits each having a first and a second stable state, each of said trigger circuits when in said first stable state being operative in response to a pulse to transfer to said second stable state but when in said second stable state being inoperative to transfer to said rst stable state, a gate circuit individual to and integral with each of said trigger circuits and controlled by the state of the trigger circuit to Which said gate circuit is individual, an electron discharge device individual to each of said trigger circuits and operative in response to each 1 l puise applied theretc te apply a pulse to both the trigger circuit and the gate circuit to which said device is individual, each of said gate circuits being operative when the trigger circuit to which said gate circuit is individual is in said second stable state and in response to the pulse applied thereto by the one of said electron discharge devices individual thereto for applying a pulse to the electron discharge device individual te the next adjacent one of said trigger circuits.

l15. A pulse-counting circuit comprising a plurality of trigger circuits each having a first and a second stable sta-te, two gate circuits individual to each of said trigger circuits and each eontrclled by the state of the trigger circuit to which said gate circuit is individual, and an electron discharge device individual to each of said gatecircuit's, each of said devices being operative in response to each puisev applied there tc to apply a pulse beth to the trigger circuit and to the gate circuit to which vsaid device is individual, each of said trigger circuits being re sponsive to a pulse from one of the devices individual thereto to shift from said first to said s'ccodstable state only and responsive to a pulse frein the other of the devices individual thereto te shiftV from said seccnd to said first stable state nly, ene f said gate circuits being operative whenthe trigger circuit to which it is individual is in one of said stable states and in response 3Q tc the puise applied thereto by the one of said devices which is individual thereto for applying a pulse to the electron discharge device individual to the 'next succeeding trigger circuit, the other of said gate circuits being operative when the trigger circuit to which it is individual 'is in the Other Of its Stable statesand in response te the pulse applied thereto by the cnc of said devices which is individual thereto for applying a pulse to the electrn discharge device ini dividual to the next preceding trigger circuit.v

BRCKWAY References Cited in the file of this patent NI'I'fED STA'IES PATENTS Number Name Date 4 2,402,989 Dickinson l g g July 2, 1946 2,422,698 June 24, 194'?` 2,427,533 Overbeek Sept. 16,. 1.947 2,436,482 Miller et al. Feb; 24, 1948 2,462,275 Morton et all Feb. 22, 1949 v2,527,633 Grignon Y Oct. 81, 1950 2,536,916 Dickinson in- Dee. 21, 1945 OTHER REFERENCES YRev'ersibie Decade Counting Circuit, Victor H. Regener, The Review of Scientific Instruments;vo1ume rzL No. 1o. october, 1946. 

